<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>使用css绘制三角形</title>
  <style>
    #toTriangle{
      width: 0;
      height: 0;


      /*border-left: 50px solid blue;*/
      /*border-right: 50px solid yellow;*/
      /*border-bottom: 50px solid red;*/

      border-left-width: 50px;
      border-right-width: 50px;
      border-bottom-width: 100px;

    }
  </style>
</head>
<body>
<div id="toTriangle"></div>
</body>
</html>
